The present invention relates to improvements in apparatus for damping torsional vibrations. More particularly, the invention relates to improvements in torsional vibration damping apparatus of the type wherein rotation of input and output members with each other is desirable (or at least acceptable) but angular movements of such members relative to each other (especially beyond a certain range of such angular movements) are undesirable or even damaging.
It is known to utilize torsional vibration damping apparatus in the power trains of motor vehicles, e.g., between the rotary output component of an internal combustion engine (or another suitable prime mover) and the input component (e.g., a flywheel) of an automated or manually engageable and disengageable friction clutch which, in turn, serves to transmit variable torque to the rotary input component of a manually shiftable or automated or automatic variable-speed transmission.
A drawback of many presently known torsional vibration damping apparatus is that they are bulky, complex and expensive. This creates serious problems in the power trains of numerous types of motor vehicles. Moreover, the assembly of conventional torsional vibration damping apparatus at the locale of use (such as an automobile assembly plant) is often a time-consuming procedure involving numerous welding, riveting, shape-altering, centering and/or other operations which contribute to the cost of the power plant and of the entire motor vehicle. Still further, it is normally necessary to establish and maintain supplies of large numbers of different spare parts.
An object of the invention is to provide a torsional vibration damping apparatus which is simpler, more compact and less expensive than, but just as reliable and versatile as, heretofore known apparatus.
Another object of the invention is to provide a novel torsional vibration damping apparatus which can be utilized with particular advantage in the power trains of passenger cars and/or other types of motor vehicles.
A further object of the invention is to provide a torsional vibration damping apparatus which can be utilized with particular advantage in the power trains of compact or miniature motor vehicles.
An additional object of the invention is to provide a torsional vibration damping apparatus which can stand long periods of extensive use and wear, i.e., an apparatus whose useful life is longer (or even much longer) than that of presently known and utilized torsional vibration damping apparatus.
Still another object of the invention is to provide a torsional vibration damping apparatus which is constructed and assembled in such a way that none of its parts must be immersed in a lubricant or another fluid medium in order to be capable of standing long periods of extensive use in the power train of a motor vehicle or elsewhere.
A further object of the invention is to provide a highly effective torsional vibration damping apparatus which is superior to numerous heretofore known apparatus and which can be installed in existing power trains as a superior substitute for conventional torsional vibration damping apparatus.
Another object of the invention is to provide a novel and improved modular torsional vibration damping apparatus.
An additional object of the invention is to provide a torsional vibration damping apparatus which can be assembled, either to a large extent or even practically entirely, at the manufacturing plant in lieu of at the locale of ultimate use.
Still another object of the invention is to provide novel and improved modules for use in the above outlined torsional vibration damping apparatus.
A further object of the invention is to provide novel and improved damper means for use in the above outlined torsional vibration damping apparatus.
Another object of the invention is to provide novel and improved methods of assembling torsional vibration damping apparatus for use in the power trains of motor vehicles.
An additional object of the invention is to provide a power train which embodies the above outlined torsional vibration damping apparatus.
Still another object of the invention is to provide novel and improved connections between various constituents of the improved torsional vibration damping apparatus, such as between the input and output members and the elements of a damper which operates between the input and output members.
A further object of the invention is to provide the apparatus with novel and improved means for limiting the magnitude of torque which can be transmitted from a prime mover to a transmission or the like.
Another object of the invention is to provide novel and improved input and output members for use in the above outlined torsional vibration damping apparatus.
An additional object of the invention is to provide the apparatus with novel and improved means for centering its input and output members relative to each other.
Still another object of the invention is to provide a novel and improved distribution of component parts which contributes to compactness of the improved apparatus as seen in the axial and/or in the radial direction of its rotary constituents.
A further object of the invention is to design the various constituents of the apparatus in such a way that its fasteners and/or other removable or separable or exchangeable parts are readily accessible to standard tools.
The invention resides in the provision of an apparatus for damping torsional vibrations, particularly in the power trains of motor vehicles. The improved apparatus comprises rotary input and output members which are arranged to carry out rotary movements with and relative to each other, particularly about a common axis, and at least one damper which operates between and is arranged to oppose at least some (e.g., predetermined stages of) rotary movements of the input and output members relative to each other. The damper comprises at least one energy storing device, e.g., a straight or arcuate coil spring or a set of interfitted coil springs.
It is preferred to provide the input and output members with suitable flywheels or sets of flywheels. Thus, the input member can include or constitute a primary flywheel which can be driven by the output component (such as a camshaft or a crankshaft) of an internal combustion engine, and the output member can comprise or constitute a secondary flywheel which can serve to transmit torque to the input element of a transmission, e.g., by way of a friction clutch. The damper of such apparatus is or can be arranged to oppose at least some rotary movements of the primary and secondary flywheels relative to each other.
If the output member is to drive the input shaft of a transmission by way of a friction clutch, the secondary flywheel can be provided with an annular friction surface which faces away from the input member and the clutch can comprise a pressure plate, a clutch disc between the friction surface of the secondary flywheel and the pressure plate, and means (e.g., a clutch spring which can constitute a diaphragm spring) for moving the pressure plate relative to the friction surface between a plurality of different axial positions in at least one of which the pressure plate causes the clutch disc to bear against the friction surface and to thus receive torque from the secondary flywheel, i.e., from the output member. The clutch disc can transmit torque to the input shaft of the transmission.
The damper can comprise at least one rotary input element serving to receive torque from the primary flywheel, and a rotary output element which is rotatable relative to the at least one input element and can serve to transmit torque to the secondary flywheel. The at least one energy storing device of the damper is then interposed between portions of the at least one input element and of the output element to yieldably oppose rotation of the at least one input element and the output element relative to each other. Such apparatus can further comprise a first torque transmitting connection between the input member and the at least one input element of the damper and a second torque transmitting connection between the output element of the damper and the output member. The at least one energy storing device can be located at a first radial distance from the common axis of the input and output members, and each of the two connections can be located at a greater second radial distance from such axis.
The just described embodiment of the improved apparatus can further comprise a frictional connection between at least one of the flywheels and (a) the at least one input element or (b) the output element. Alternatively, one can provide a form-locking connection between one of the flywheels and the at least one input element or between one of the flywheels and the output element of the damper.
A first torque transmitting connection can be provided between the input member and the at least one input element, and a second torque transmitting connection can be provided between the output element and the output member. One of these connections can be installed at a first radial distance, and the other of these connections can be installed at a different second radial distance from the common axis of the input and output members.
It is also possible to provide a frictional connection between one of the flywheels and the respective element of the damper, and a form-locking connection between the other flywheel and the other element of the damper; the form-locking connection can be disposed at a first radial distance, and the frictional connection can be disposed at a greater second radial distance from the common axis.
The apparatus can further comprise means for limiting the magnitude of the torque which can be transmitted between the primary and secondary flywheels, and such torque limiting means can include a frictional connection between one of the flywheels and the respective (input or output) element of the damper.
The torque transmitting connection between the rotary output component of the prime mover and the input member (such connection can include a set of externally threaded axially parallel fastening elements) can be placed nearer to the common axis than the energy storing device or devices of the damper, i.e., the torque transmitting connection can be disposed at a first radial distance from the common axis, and the spring or springs of the damper can be installed at a greater second radial distance from such axis.
The apparatus can further comprise at least one radial bearing (such as a journal bearing or an antifriction bearing with one or more annuli of rolling elements between two races) to serve as a means for centering the flywheels relative to each other; such centering means can be located at a first radial distance from the common axis of the flywheels, and the aforementioned fastening means between the output component of the prime mover and the input member can be located at a greater second radial distance from the axis.
One element (such as the input element) of the damper can comprise two annular parts or cheeks which are non-rotatably connected to each other, and the other element of the damper (such as the output element) can comprise a disc-shaped part (hereinafter called flange for short); at least a portion of the flange can be located between the two cheeks, as seen in the direction of the common axis of the input and output elements of the damper (such common axis preferably coincides with the common axis of the flywheels). A portion of at least one of the cheeks can form part of the centering means (such as the aforementioned radial bearing) which is installed between the two flywheels. For example, at least one of the cheeks or the flange can include a substantially cylindrical member (e.g., a sleeve or a ring) which constitutes or can constitute the radially innermost portion of the at least one cheek or of the flange and forms part of the means for centering the flywheels relative to each other. Such substantially cylindrical portion can be said to constitute an axially extending portion of the bearing and to form part of the centering means. Such part of the centering means can constitute a separately produced part which is affixed to the input or output element of the damper.
The means for centering the two flywheels relative to each other can form part of the input member or of the output member; such centering means can include an axially extending portion of the input or output member. Such part of the centering means can constitute a separately produced part which can be affixed to the primary flywheel or to the secondary flywheel.
A suitable hysteresis device (hereinafter called hysteretic damping device) can be utilized to operate between the two flywheels, preferably in parallel with the at least one energy storing device of the damper. For example, the hysteretic damping device can include or constitute a friction generating device. In accordance with one presently preferred embodiment, the at least one energy storing device of the damper is located at a first radial distance from the common axis of the flywbeels, and the hysteretic damping device can be located at a greater second radial distance from such axis.
In accordance with another presently preferred embodiment, the connection between the primary flywheel and the input element of the damper can be disposed at a first radial distance from the common axis of the flywheels, the connection between the output element of the damper and the secondary flywheel is located at a second radial distance from the common axis, and the hysteretic damping device is located at a third radial distance from the common axis; the first radial distance can be greater or less than the second radial distance, and the third radial distance is preferably greater than one but less than the other of the first and second radial distances.
Alternatively, the just discussed third radial distance (of the hysteretic damping device from the common axis) can be greater than the first as well as the second radial distance.
If the hysteretic damping device comprises a friction generating device, the latter can be set up to generate a hysteresis which varies in response to rotation of the input and output members relative to each other.
The radially outermost portion of the means for fastening the input member to the rotary output component of the prime mover can be placed at a predetermined distance from the common axis of the input and output members, and the radially innermost portion of the aforementioned flange of the damper can be located at a second radial distance from the common axis; such second radial distance preferably at least equals but can exceed the predetermined distance. The flange can be provided with at least one window for a portion of the at least one friction generating device of the damper; this window can be provided at (such as in or close to) the radially innermost portion of the flange, and the window can have an open side facing radially inwardly, i.e., toward the common axis of the flywheels.
The radially innermost portion of at least one cheek of the damper can be disposed at a radial distance from the axis which at least equals but can exceed the aforementioned predetermined distance (of the radially outermost portion of the fastening means for the input member) from such axis.
In lieu of (or in addition to) providing one or more windows for the energy storing device or devices in the flange, it is possible to provide such window or windows in at least one cheek of the damper.
The flange of the damper can be provided with one or more openings radially outwardly of the energy storing device or devices; such opening or openings provide room for the passage of one or more fastener means serving to fixedly secure the two cheeks of the damper to each other. The opening or openings of the flange can extend circumferentially of the input and output elements of the damper.
The primary flywheel can include a wall which extends radially of the common axis of the two flywheels; a radially outer portion of the flange can be placed next to and can be fixedly connected with such wall by suitable fastener means. Those portions of the wall and of the flange which are located radially inwardly of the fastener means can be spaced apart from each other to provide room for a portion of or for an entire hysteretic damping device. Distancing means can be interposed between the wall and the flange, at least in the region of the fastener means; such distancing means can comprise an annular mass.
A multi-stage torque limiting connection can be installed between one of the input and output elements of the damper and one of the primary and secondary flywheels.
The apparatus can comprise a module which includes the secondary flywheel, the pressure plate of the aforementioned friction clutch (which can be used to transmit torque from the secondary flywheel to the input shaft of the transmission in a power train), and a clutch disc which can be positioned between the secondary flywheel and the pressure plate and has a hub connectable with the input shaft of the transmission. The module can be mounted on the output element of the damper.
If the improved apparatus comprises or cooperates with a friction clutch, that side of the secondary flywheel which faces away from the primary flywheel can be provided with the aforementioned friction surface which is or which can be located at a predetermined radial distance from the common axis of the flywheels. If such apparatus further comprises torque limiting means, the latter can be placed at or close to such predetermined distance from the common axis.
The torque limiting means can operate between the input and output members of the improved apparatus and can include means for generating slip torque. Such torque generating means can include a resilient element which is arranged to store at least some energy in response to connection of the friction clutch with the secondary flywheel. The resilient element can comprise or constitute a diaphragm spring.
One of the flywheels can be provided with at least one opening affording access to and manipulation of suitable fastening means serving to secure the output element of the damper to the other flywheel. Such fastening means can comprise one or more rivets. The other flywheel can constitute the secondary flywheel and is then normally provided with the aforementioned friction surface for engagement by the friction linings of the clutch disc which transmits torque to the input shaft of the transmission. The opening or openings of the one flywheel are or can be provided at such radial distance from the common axis of the flywheels that they overlap the friction surface of the secondary flywheel (as seen in the direction of the common axis of the flywheels).
The distribution of various constituents of the improved torsional vibration damping apparatus in the radial direction of the common axis of the flywheels can be such that (a) the aforementioned radial bearing between the flywheels is located at a first radial distance from the common axis, (b) the means for fastening the input member (e.g., the primary flywheel) to the rotary output component of a prime mover is located at a greater second radial distance from the axis, (c) the at least one energy storing device of the damper is located at a greater third radial distance from the axis, (d) the torque limiting means an/or the hysteretic damping device is located at a greater fourth radial distance from the axis, and (e) at least one axial extension of the primary flywheel is located at a fifth radial distance greater than the fourth radial distance from the common axis.
The radially outer portion of the primary flywheel can include at least one annular mass, particularly a mass having several layers of folded sheet material, especially a metallic sheet material. The aforementioned radial wall of the primary flywheel can be of one piece with the annular mass; this wall can be provided with one or more openings for fastening means which serves to secure the input member to the rotary output constituent or component of a prime mover. In lieu of being of one piece with the annular mass, the radial wall can constitute a separately produced part; the input member then further comprises means for securing the annular mass to the radially outer portion of the wall.
The annular mass which constitutes or is carried by the radially outermost portion of the primary flywheel can support or can be made of one piece with a starter gear. Alternatively, or in addition to the starter gear, the annular mass at the radially outer portion of the primary flywheel can carry or can be made of one piece with suitable engine management indicia (for example, such indicia can be tracked by one or more speed monitoring and/or other sensors).
If at least one of the two flywheels is movable axially relative to the other flywheel, the hysteretic damping device (which preferably operates in parallel with the energy storing device or devices of the damper) can include at least one resilient element (e.g., a diaphragm spring) which is arranged to bias the at least one flywheel axially toward the other flywheel.
In lieu of forming part of the aforediscussed module (which includes at least some constituents of the friction clutch), the secondary flyweel can form part of a module which further includes the damper and is connectable with the primary flywheel. Such module can include or encompass one or more additional parts, such as the aforementioned friction clutch including the clutch disc which is insertable between a pressure plate of the friction clutch and the friction surface of the secondary flywheel. The friction clutch can be mounted on or otherwise carried by the secondary flywheel.
The aforementioned hysteretic damping device can be designed in such a way that it comprises at least one friction ring which is surrounded by a portion of the input member or output member. Alternatively, the hysteretic damping device can comprise friction generating elements (e.g., an annular array of such elements) confined by a suitable annular guide surface which surrounds and guides the friction generating elements and can have its center on the common axis of the flywheels.
The means for limiting the magnitude of the torque which can be transmitted between the input and output members can comprise at least one resilient element (such as a diaphragm spring) which is stressed in the axial direction of the flywheels to assist the clutch spring (such clutch spring can constitute or include a second diaphragm spring). Suitable means can be provided for affixing the resilient element of the torque limiting means to the clutch housing.
If the apparatus includes a module composed of or including the secondary flywheel, a friction clutch adjacent the friction surface of the secondary flywheel, and a clutch disc between the friction surface and the clutch, the housing of the clutch can be secured to the secondary flywheel or to the damper by fastener means which are accessible at one side of the secondary flywheel, namely the side located opposite the friction surface and confronting the primary flywheel. The fastener means can comprise external threads receivable in tapped bores of the clutch housing. Depending upon the interpretation of the term xe2x80x9cfriction clutchxe2x80x9d, the clutch disc can be considered as a component part of such clutch or as a discrete part.
It is also possible to mount the fastener means for securing the clutch housing to the output member (e.g., to the secondary flywheel) in such a way that the constituents (e.g., bolts or screws or the like) are accessible for insertion or removal at the friction surface side of the secondary flywheel. The fastener means can be parallel to the common axis of the flywheels.
At least one of the normally two cheeks forming part of the input element of the damper can be safely secured to the primary flywheel by two connecting means, namely a first connecting means located radially outwardly of the energy storing device or devices of the damper, and a second connecting means located radially inwardly of such energy storing device or devices. The first connecting means can comprise one or more rivets, and the second connecting means can further serve as the aforementioned means for securing the input member (e.g., the primary flywheel) to the rotary output component of the prime mover.
In accordance with one presently preferred embodiment of the damper, the latter comprises several (particularly five) energy storing devices forming an annular array spacedly surrounding the common axis of the flywheels. Each such energy storing device can be located at or at least close to the same radial distance from the common axis.
The torque limiting device of the improved apparatus can be installed to operate between the output element of the damper and the secondary flywheel. If a clutch is being utilized in such apparatus, it is attachable to and detachable from the secondary flywheel. The torque limiting means can comprise at least one resilient element (such as a diaphragm spring) which is stressed in the direction of the common axis of the flywheels in response to attachment of the friction clutch to the secondary flywheel, and which is caused or permitted to dissipate at least some energy in response to detachment of the clutch from the secondary flywheel.
It has been found that, regardless of whether utilized individually or in any one of a number of different combinations with each other, the aforediscussed features contribute to simplicity, reliability, compactness (both in the direction of the common axis of the primary and secondary flywheels and in a direction at right angles to such axis) and numerous other advantages of the improved torsional vibration damping apparatus as well as of the power train which cooperates with or embodies such apparatus.
The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved torsional vibration damping apparatus itself, however, both as to its construction and the mode of assembling, installing and operating the same, together with numerous additional important and advantageous features and attributes thereof, will be best understood upon perusal of the following detailed description of certain presently preferred specific embodiments with reference to the accompanying drawings.